Yes you will need a permit. 1) you will need to add outlets on each wall as per code...and of course switches for any lights or fans.

Poor lighting.

We do some cosmetic improvements to bring homes to our standard, typically carpet and paint, upgrade lighting etc.

There are many light companies to choose from here.

If the prices work where you are, I think with your experience, you could go right into a four-plex and do fine, especially if it was light to moderate value-add because of your knowledge and connections.

There is a lot of weight on marketing, and a lot of inputs to that cycle.

They were very light and didn't last long. 

BUT for certain rural areas it's worth it's weight in gold because of the reliability factor vs an unreliable or expensive existing utility structure. 

If it is block construction the engineers will make you beef up the slab and add piles to support the new weight of the second floor.

Based on the local market, $15k for renovations seems light—have you had contractors confirm this budget?